This invention relates to a roof space ventilator.
The continuing awareness within the building industry of the energy crisis has led to an increasing use of high levels of insulation in houses, and particularly in roof spaces.
The use of high levels of insulation in roof spaces has two principle effects. Firstly, the temperature of the roof becomes colder leading to increased condensation; and secondly, ventilation of the roof space through the eaves of the house is impeded by the insulation. In view of this it is essential to ensure that an adequate ventilation path is maintained for atmospheric air through the eaves into and out of the roof space.
Further problems may arise when using loose felt or granulated insulation materials which have to be prevented from ingress to the eaves by a physical barrier of some kind.
There are ventilators available which try to provide an air passageway through the eaves and similtaneously prevent the ingress of insulating material into the eaves.
An example of such a ventilator is described in United Kingdom patent specification No. 2,070,662B. The ventilator described in this specification is foldable and has two portions which have to be secured to the rafters and the roof joists in order to maintain the ventilator in position. Installation of this ventilator can be time consuming because it is necessary to align correctly the portions with the joists and rafters before they can be secured thereto.
Another ventilator is described in United Kingdom patent specification No. 2,088,924B. This ventilator is subject to similar problems to the ventilator described above.
Similar ventilators are described in, for example, U.S. Pat. Nos. 3,863,553, 4,069,628 and 4,189,878.
More advanced ventilators have been developed which have a plurality of elongate ribs extending parallel to the air flow path so that air may flow between adjacent ribs. Examples of such ventilators are described in U.S. Pat. Nos. 3,972,164 and 3,797,180, in United Kingdom patent application No. 2,127,060A, and in International patent application No. WO 80/01702. Problems can arise with these ventilators. If the spacing between the ribs is too large then the sarking felt can sag between the ribs and obstruct the ribs. If the spacing is reduced to avoid this problem then the air flow is obstructed by the large number of ribs. Furthermore these ventilators are not strong enough to withstand the loading applied to the sarking felt and are not adapted to prevent the ingress of insulation material to the eaves.
None of the ventilators described in the above specifications are easy to install in the roof structure, and many of them cannot be installed in buildings after the roof structures have been constructed.